Such a conventional transmission imager is known as disclosed in Japanese Patent Laid-open Publication No. 2001-153819 which includes a first imaging means for producing an X-ray tomographic image and a second imaging means for producing a variable angle transmission image. The conventional transmission imager of the citation has an image intensifier provided fixedly off to a location lower than an X ray radiation source with its detecting surface extending horizontally for producing a tomographic image by X-ray laminography technique. Since the technique is intended to turn the X ray image in synchronization with the rotating movement of a specimen for producing tomographic images at the plane of turning, the detecting surface at the center of the detector is at a right angle to a reference line which extends from the center to the target.
It is however necessary for determining the location of producing a laminography image to prepare a series of transmission images at different angles. This action of preparing the transmission images is commonly carried out by the second imaging means or radiation detector being shifted in its angular position. Accordingly, the radiation detector has to be shifted in a succession to predetermined angles for producing a series of the transmission images at different angles, hence declining the efficiency of the image producing action. Also, its shifting action requires an intricate shifting mechanism thus increasing the overall cost.
It is moreover essential for implementing the conventional apparatus to permit X rays to be radiated throughout a wider angle from the X ray radiation source and received by the laminograph. This requires a transmission type of the X ray radiation source. As the result, the energy of radiation will be declined after passing the target hence producing an image, which is clear at the center and both sides, only with difficulty.
It is an object of the present invention, in view of the above aspect, to provide a transmission imager which can produce a transmission image from two or more different view points with the use of a simpler arrangement.